Why ratio matters more than “scoops”
The same volume of beans varies 30–40 % in weight depending on grind and roast. Once you switch from scoops to weight you’ll notice that “the same amount of coffee” on the same scale gives you a noticeably more consistent cup, with less bitterness and more brightness. The ratio (coffee : water) is the single most important variable in extraction — more important than grind, water temperature or pour technique.
Adjusting to taste
If your brew tastes bitter and dry, try a wider ratio (more water per gram of coffee — e.g. move from 1:16 to 1:17). If it tastes thin and sour, try a tighter ratio (1:15) or a finer grind. The ratio sets total dissolved solids; grind size sets extraction yield. Adjust one at a time.
The SCA Brewing Control Chart
The SCA defines an “ideal cup” as 18–22 % extraction yield (how much of the bean ends up dissolved) and 1.15–1.35 % total dissolved solids (the strength of the resulting brew). The ratios in this calculator land in that zone for each brew method. If you want to fine-tune, a refractometer (e.g. Atago PAL-COFFEE or VST) measures TDS directly.